Selective Hydrogenation Of Phenol On Bimetallic Catalyst Using Ethanol As Hydrogen Source

Cyclohexanone is an important industrial raw material which is widely used and owns a huge market demand. Many researchers have contributed to the area of phenol selective hydrogenation to cyclohexanone for the advantage of mild reaction conditions and high cyclohexanone selectivity. In this work, the phenol hydrogenation to cyclohexanone on bimetallic catalyst using ethanol as hydrogen source with a good phenol conversion and cyclohexanone selectivity has been developed.Firstly, supported Pd catalysts:Pd/ZrO2, Pd/CeO2 and Pd/Al2O3 was prepared by incipient wetness impregnation method. By comparing, we found that using ZrO2 as catalyst support have a better catalytic activity. On the other hand, bimetallic catalyst Ru-Pd/ZrO2 was prepared by incipient wetness impregnation method for a better reaction effect. The effects of reaction temperature(250℃,275℃ and 300℃) on the phenol conversion, the selectivity of liquid products and the yields of gas products with the phenol concentration of 20.4g/L was investigated on Ru-Pd/ZrO2. In this study, the main liquid products are cyclohexanone (19.35%-71.22%), cyclohexanol (0.65%-20.51%) and cyclohexane (0.14%-19.58%). The main gas products are CH4 (0.75mmmol/g-7.93mmol/g), H2 (0.91mmmol/g-5.03mmol/g) and CO2 (0.44mmmol/g-5.25mmol/g). And the results show that higher conversion of phenol and ethanol, higher selectivity of cyclohexane could be achieved with high temperature, however, high temperature is adverse for the selectivity of cyclohexanone.The effects of reaction time (0min-240min) on the phenol selective hydrogenation indicate that longer reaction time was favorable for a high phenol and ethanol conversion. The yields of liquid and gas products increased with reaction time increasing under low temperature, however, the yields of liquid and gas products remained relatively constant with the reaction time over 60min under high temperature.The effects of ethanol content also have been explored. The results indicate that the over content of ethanol (>5%) is detrimental to the liquid generated under low reaction temperature. And it is interesting to find that the effect of ethanol content is weak on the produce of liquids products under high temperature. On the other hand, the yields of gas products, especially the yields of H2 increase with the increasing of ethanol content.